Aircraft Emission Simulations Help "Clear the Air"
With tens of thousands of tons of Nitrogen Oxide (NOx) emissions being released into the air we breathe annually—in the United States alone—it is extremely important to find ways to reduce these harmful pollutants. Among other things, NOx emissions cause smog, acid rain, asthma, and ozone layer depletion.
One way NASA is doing its part to reduce NOx emissions is by using a state-of-the-art computational fluid dynamics (CFD) software package called the National Combustion Code (NCC) to simulate new concepts for gas turbine engines designed to lower emissions produced during combustion.
Using high-end computing resources at the NASA Advanced Supercomputing (NAS) facility located at Moffett Field, Calif., scientists at NASA Glenn Research Center in Cleveland, Ohio run massive, highly complex simulations of potential low-emission engine designs. Current simulations consume anywhere from 96 to over 4,000 processors on the Agency's Pleiades supercomputer.
A transient flow mixing study of a Lean Direct Injection (LDI) combustor swirler. Pathlines are colored by axial velocity. The white isosurface of pressure elucidates the vortex core resulting from the swirler. (Jay Horowitz, NASA Glenn)
"There are no straightforward, direct approaches in combustion modeling. Combustion is described by very complex equations that cannot be directly solved—in other words, use of a supercomputer is an absolute must," said Anthony Iannetti, a researcher in the Combustion Branch of NASA Glenn's Aeropropulsion Division.
Iannetti is using NCC particularly to explore Lean Direct Injection (LDI) concepts, which were developed to reduce NOx emissions, or smog, and may decrease fuel consumption. In LDI, liquid fuel is sprayed directly in the combustor using multiple fuel injector modules. The goal of LDI is to violently mix the fuel and air so the resulting flame is mostly premixed. This combustion concept works well at full power conditions. At low power conditions, the overall air/fuel ratio is too lean to sustain stable combustion.
Over the past several years, NASA's work with LDI and other lean combustion concepts has been gradually transferred to industrial aircraft gas turbine engines such as General Electric's GE-90 engine used for the Boeing 777 aircraft and the GE-NX turbofan. These engines produce far fewer NOx emissions than past jet engines.
More information:
+ The National Combustion Code: Simulations from Scalability (PDF-544 KB)
Contact information:
Anthony Iannetti
NASA Glenn Research Center
Combustion Branch, Aeropropulsion Division
Office: 216-433-5586
Anthony.C.Iannetti@nasa.gov
